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1 0 : // Distributed under the MIT License.
2 : // See LICENSE.txt for details.
3 :
4 : #pragma once
5 :
6 : // IWYU pragma: begin_exports
7 : #include <boost/parameter/name.hpp>
8 : #include <boost/preprocessor/arithmetic/inc.hpp>
9 : #include <boost/preprocessor/control/expr_iif.hpp>
10 : #include <boost/preprocessor/control/iif.hpp>
11 : #include <boost/preprocessor/control/while.hpp>
12 : #include <boost/preprocessor/list/adt.hpp>
13 : #include <boost/preprocessor/list/fold_left.hpp>
14 : #include <boost/preprocessor/list/fold_right.hpp>
15 : #include <boost/preprocessor/list/for_each_product.hpp>
16 : #include <boost/preprocessor/list/size.hpp>
17 : #include <boost/preprocessor/list/to_tuple.hpp>
18 : #include <boost/preprocessor/list/transform.hpp>
19 : #include <boost/preprocessor/logical/bitand.hpp>
20 : #include <boost/preprocessor/logical/bool.hpp>
21 : #include <boost/preprocessor/logical/compl.hpp>
22 : #include <boost/preprocessor/repetition/for.hpp>
23 : #include <boost/preprocessor/tuple/elem.hpp>
24 : #include <boost/preprocessor/tuple/reverse.hpp>
25 : #include <boost/preprocessor/tuple/size.hpp>
26 : #include <boost/preprocessor/tuple/to_list.hpp>
27 : #include <boost/preprocessor/variadic/elem.hpp>
28 : #include <boost/preprocessor/variadic/to_list.hpp>
29 : // IWYU pragma: end_exports
30 :
31 : /// \cond
32 : #define GENERATE_INSTANTIATIONS_DO_PRODUCT(INSTANTIATION_MACRO, LIST_OF_LISTS) \
33 : BOOST_PP_LIST_FOR_EACH_PRODUCT(INSTANTIATION_MACRO, \
34 : BOOST_PP_LIST_SIZE(LIST_OF_LISTS), \
35 : BOOST_PP_LIST_TO_TUPLE(LIST_OF_LISTS))
36 :
37 : #define GENERATE_INSTANTIATION_TUPLES_TO_LISTS(d, _, elem) \
38 : BOOST_PP_TUPLE_TO_LIST(BOOST_PP_TUPLE_SIZE(elem), elem)
39 : /// \endcond
40 :
41 : /*!
42 : * \ingroup UtilitiesGroup
43 : * \brief Macro useful for generating many explicit instantiations of function
44 : * or class templates
45 : *
46 : * It is often necessary to generate explicit instantiations of function or
47 : * class templates. Since the total number of explicit instantiations scales as
48 : * the product of the number of possible number of parameter values of each
49 : * template parameter, this quickly becomes tedious. This macro allows you to
50 : * easily generate hundreds of explicit instantiations.
51 : *
52 : * The first argument to the macro is a macro that takes two arguments and is
53 : * described below. The remaining arguments are macro-tuples, e.g. `(1, 2, 3)`.
54 : * The Cartesian product of the macro-tuples is then computed and each term is
55 : * passed as a tuple as the second argument to the `INSTANTIATION_MACRO`. The
56 : * first argument to the `INSTANTIATION_MACRO` is a Boost.Preprocessor internal
57 : * variable so just make it `_`. The `INSTANTIATION(_, data)` macro below serves
58 : * as an example. A concrete example is generating explicit instantiations of
59 : * the class `Index<Dim>` for `Dim = 0,1,2,3`, which you would do as follows:
60 : *
61 : * \code
62 : * #define GET_DIM(data) BOOST_PP_TUPLE_ELEM(0, data)
63 : *
64 : * #define INSTANTIATION(_, data) \
65 : * template class Index<GET_DIM(data)>;
66 : *
67 : * GENERATE_INSTANTIATIONS(INSTANTIATION, (0, 1, 2, 3))
68 : *
69 : * #undef GET_DIM
70 : * #undef INSTANTIATION
71 : * \endcode
72 : *
73 : * This will generate:
74 : *
75 : * \code
76 : * template class Index<0>;
77 : * template class Index<1>;
78 : * template class Index<2>;
79 : * template class Index<3>;
80 : * \endcode
81 : *
82 : * It is also possible to generate explicit instantiations for multiple classes
83 : * or functions in a single call to `GENERATE_INSTANTIATIONS`. For example, the
84 : * (in)equivalence operators can be generated using:
85 : *
86 : * \code
87 : * #define GET_DIM(data) BOOST_PP_TUPLE_ELEM(0, data)
88 : * #define GEN_OP(op, dim) \
89 : * template bool operator op(const Index<dim>& lhs, \
90 : * const Index<dim>& rhs);
91 : * #define INSTANTIATION(_, data) \
92 : * template class Index<GET_DIM(data)>; \
93 : * GEN_OP(==, GET_DIM(data)) \
94 : * GEN_OP(!=, GET_DIM(data))
95 : *
96 : * GENERATE_INSTANTIATIONS(INSTANTIATION, (0, 1, 2, 3))
97 : *
98 : * #undef GET_DIM
99 : * #undef GEN_OP
100 : * #undef INSTANTIATION
101 : * \endcode
102 : *
103 : * which will result in the instantiations:
104 : *
105 : * \code
106 : * template class Index<0>;
107 : * template bool operator==(const Index<0>& lhs, const Index<0>& rhs);
108 : * template bool operator!=(const Index<0>& lhs, const Index<0>& rhs);
109 : * template class Index<1>;
110 : * template bool operator==(const Index<1>& lhs, const Index<1>& rhs);
111 : * template bool operator!=(const Index<1>& lhs, const Index<1>& rhs);
112 : * template class Index<2>;
113 : * template bool operator==(const Index<2>& lhs, const Index<2>& rhs);
114 : * template bool operator!=(const Index<2>& lhs, const Index<2>& rhs);
115 : * template class Index<3>;
116 : * template bool operator==(const Index<3>& lhs, const Index<3>& rhs);
117 : * template bool operator!=(const Index<3>& lhs, const Index<3>& rhs);
118 : * \endcode
119 : *
120 : * Now let's look at generating instantiations of member function templates of
121 : * class templates, which will be a common use case. In this example we generate
122 : * explicit instantiations of all the member function templates of the class
123 : * `ScalarWave::Solutions::PlaneWave`. In total, for `Dim = 1,2,3` and types
124 : * `double` and `DataVector` this is about 42 explicit instantiations, which
125 : * would be extremely annoying to write by hand. The macro code is surprisingly
126 : * simple:
127 : *
128 : * \code
129 : * #define DIM(data) BOOST_PP_TUPLE_ELEM(0, data)
130 : * #define DTYPE(data) BOOST_PP_TUPLE_ELEM(1, data)
131 : *
132 : * #define INSTANTIATE(_, data) \
133 : * template Scalar<DTYPE(data)> \
134 : * ScalarWave::Solutions::PlaneWave<DIM(data)>::psi( \
135 : * const tnsr::I<DTYPE(data), DIM(data)>& x, double t) const; \
136 : * template Scalar<DTYPE(data)> \
137 : * ScalarWave::Solutions::PlaneWave<DIM(data)>::dpsi_dt( \
138 : * const tnsr::I<DTYPE(data), DIM(data)>& x, double t) const;
139 : *
140 : * GENERATE_INSTANTIATIONS(INSTANTIATE, (1, 2, 3), (double, DataVector))
141 : *
142 : * #undef DIM
143 : * #undef DTYPE
144 : * #undef INSTANTIATE
145 : * \endcode
146 : *
147 : * We don't show the result from preprocessor since for all of the member
148 : * functions of `PlaneWave` the total output is approximately 150 lines, but you
149 : * can hopefully see the benefits of generating explicit instantiations using
150 : * the `GENERATE_INSTANTIATIONS` way.
151 : *
152 : * One thing that can be difficult is debugging metaprograms (be they template
153 : * or macro-based). To this end we provide a make target `DebugPreprocessor`
154 : * which prints the output of running the preprocessor on the file
155 : * `src/Executables/DebugPreprocessor/DebugPreprocessor.cpp`.
156 : * Note that the output of the `GENERATE_INSTANTIATIONS` macro will be on a
157 : * single line, so it often proves useful to copy-paste the output into an
158 : * editor and run clang-format over the code so it's easier to reason about.
159 : */
160 1 : #define GENERATE_INSTANTIATIONS(INSTANTIATION_MACRO, ...) \
161 : GENERATE_INSTANTIATIONS_DO_PRODUCT( \
162 : INSTANTIATION_MACRO, \
163 : BOOST_PP_LIST_TRANSFORM(GENERATE_INSTANTIATION_TUPLES_TO_LISTS, _, \
164 : BOOST_PP_VARIADIC_TO_LIST(__VA_ARGS__)))
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